


Every Version of You

by thisgirlsays22



Category: Shingeki no Kyojin | Attack on Titan
Genre: Alternate Universe - Merpeople, Alternate Universe - Modern Setting, Anal Fingering, Bottom Eren Yeager, EreriPrompts11, Established Relationship, Fluff, M/M, Mer Smut, Merman!Levi, Modern Era, Oral Sex, Shifter Levi, Smut, Top Levi (Shingeki no Kyojin), mer Levi, pining eren
Language: English
Status: Completed
Published: 2019-03-19
Updated: 2019-03-19
Packaged: 2019-11-24 11:42:05
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,526
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18164747
Author URL: https://archiveofourown.org/users/thisgirlsays22/pseuds/thisgirlsays22
Summary: It wasn’t as though Levi had completely shut down the idea of having sex when he shifted, it was that he needed time, and it would be wrong for Eren to keep pushing. So instead he waited, and yearned, and waited some more.





	Every Version of You

**Author's Note:**

  * For [KioneM](https://archiveofourown.org/users/KioneM/gifts).



> Happy birthday, Mara!! For you, I attempted mer!smut. I love you and am so grateful for your friendship and the art you spoil us all with <3 I hope you enjoy!!

Eren loved to watch Levi swim. Body slicing through the lake’s clear water, the blues of his tail glittering when the sun hit them just right. This was their third visit to the Ackerman family’s lake house, and Eren looked forward to the quiet week ahead.

“Caught dinner.” The (mostly) human half of Levi’s body had emerged from the water and, with a small smirk, his webbed hands dropped a still flopping, gasping catfish down on the rocky ground in front of Eren. The gills on the side of Levi’s neck fluttered in the fresh air.

“I think we’ll need another,” Eren said, wanting to watch Levi dive back in, aquamarine tail rising to the surface as he disappeared below the water. Full of an odd longing, Eren tugged on the strings of his hoodie, pulling the fabric tighter to protect against the chilly November air.

That small smirk again. “Well, alright then.” Levi dove back under.

Eren put the fish out of its misery and began gutting it with Levi’s silver pocket knife as he waited.

The second time Levi emerged, he got out of the water the whole way, legs and all. No trace left of the his translucent fins, his shimmery tail. A flicker of disappointment went through Eren.

“You’re indecent,” Eren teased, catching sight of Levi’s cock. “No one wants to see that. Put it away!”

Levi chuckled, teeth chattering as he rooted around in his backpack for his towel and clothes.

“I could warm you up,” Eren offered lowly.

Seeing Levi in his mer form always got Eren worked up. His eyes roamed Levi’s body hungrily, wishing for once he’d let Eren love him in his other form. Levi didn’t acknowledge the comment.

Levi grabbed his bag. “Well, come on. What are you waiting for? I’m starving.”

Eren cast one final look out at the clear lake, nestled between the mountains. The sky beyond looked vast, and Eren felt a little hopeful as he gazed out at the horizon. Like the trip was full of promise and possibility.

He followed Levi back to the house.  

 

 

 

It wasn’t as though Levi had completely shut down the idea of having sex when he shifted, it was that he needed time, and it would be wrong for Eren to keep pushing. So instead he waited, and yearned, and waited some more.

He understood. At first, Eren was wary of fucking Levi when he wasn’t entirely human. Would doing so make him a fish-loving, bestiality-inclined freak?

“You’re being an idiot,” Levi had said. “Besides, you’re the fucking animal.”

So yeah, Eren understood having hang-ups about the whole thing, but he didn’t quite understand what Levi’s were; they were clearly not one in the same.  

He didn’t even quite understand his fascination, his desire. Maybe it stemmed from the envy Eren felt that Levi had the chance to alter himself so thoroughly, to wear a new skin, whenever he pleased. Something Eren longed for too. Perhaps if he fused Levi and himself together, if it felt like they were one, then Eren could alter himself as well.

 

 

 

Tonight was their first night at the lake house, so unsurprisingly Levi was dusting all the surfaces in his rapid, efficient way while the fish was in the oven.

Eren had joined in without much enthusiasm and kept getting distracted by how good Levi’s ass looked in his jeans. _Maybe it’s better he won’t let me fuck him when he’s a mermaid--man. Shit. He’s going to kill me if I keep getting that wrong. Would he fuck me or would I have to figure out how to fuck him? I’d miss his ass. He has a great ass._

“What the fuck are you doing?” Levi had stopped cleaning and was staring at Eren in disbelief. “Now isn’t the time for daydreaming. Have you seen what a shithole this place is?”

“You’re the one who wanted to go for a swim first and then put dinner on,” Eren whined. “Now I’m tired.”

“Don’t be such a baby.”

“I told you we should have just hired a cleaner to come last week.”

Levi waved a hand. “Tch. Waste of money. Go get the vacuum or something. If you’ve got time for leaning, you’ve got time for cleaning.”

“I wasn’t leaning, I was standing up straight and admiring your ass.”

“Oh, thanks,” Levi’s voice was flat, but that wasn’t his sarcastic tone, so Eren took it as a win. “Now go vacuum.”

Eren paused in the doorway, biting his lower lip.

Levi turned to look at him and raised an eyebrow. “You okay?”

“I’ve just been thinking again. Since I saw you in the water,” Eren said haltingly. “Have you thought more about us--” he gestured between them, raising his eyebrows “--while you’ve shifted.”

“Mm.” Levi shrugged. “A little.”

“Oh,” Eren said. After a beat, he realised Levi wasn’t going to add anything. “So I’ll just...go get that vacuum then.” He turned on his heels, embarrassed at his lack of tact. Hoping to impress Levi, he vacuumed all the more diligently.

 

 

 

On their third night at the lake house, apropos of nothing, Levi said, “You still want to be a fish fucker?” He was reorganising one of the bookshelves--“Kenny must have been here last, he never puts anything away in the right place.”--on the other side of the room, and Eren was sure he hadn’t heard him properly. Levi’s vague answer the other night had led Eren to believe the discussion would not be picked up for some time (or ever again.)

It was so out of the blue that Eren could only manage to pause his video game and stare blankly at Levi’s back. “What?”

“I’m not saying it again.” The tips of Levi’s ears had gone red, but he was still fussing with the bookshelf.

“Oh god,” Eren breathed, the implication of Levi’s words finally hitting him, “you’re really going to let me?”

“Yes.”

“Seriously?”

Now Levi turned to glare at him. “Yes.”

“No but like for real? You’re not fucking with me?”

“If you don’t knock it off, then it won’t be for real.”

“Sorry sorry! I’m just wow. Wow.” Though he was curious what was going on in Levi’s head right now, what was to thank or blame for his sudden change of heart, Eren feared if he started to push, Levi would rescind the offer. “So how do you want to do this?”

 

 

 

Once the initial thrill wore off one thing became clear: logistically, it was a nightmare.

It made a sort of weird sense; their whole _relationship_ had been a bit of a logistical nightmare. An innocent question like, “So how did you two meet?” required planning, the harmless twisting of facts, the synchronisation of stories.

Eren couldn’t exactly answer, “Well, I was swimming in the ocean when I was seventeen when a rip tide pulled me under out of nowhere, and then the lifeguard who was also part mermaid-- _man_ damn it. Shit sorry--saved me. I couldn’t stay away from the beach after that and when I finally turned eighteen he fucked me silly on a beach towel and wouldn’t stop complaining about sand in his ass. Yep that’s the love of my life Levi Ackerman for ya. He comes from a long line of merfolk who seem to own a lot of waterfront properties. Great eye for real estate, those mer men and women. Levi and I have been together for about three years now and he still won’t let me fuck him in his mer form, which is a real bummer.”

Now that Levi had finally said yes after all this time, it became clear that the biggest problem was where and how they would do the deed.

“What about the lake?”

Levi snorted. “It’s too fucking cold, especially for you. Your dick’ll shrink to the size of a peanut.”

“Point taken. What about the bathtub?”

Levi scrubbed a hand over his face. “I’m fine outside of water for about two hours. I’ll shift in the tub and you can--” he cringed “--carry me to the bedroom. But put a towel down so the sheets don’t get wet and disgusting.”

Once they’d agreed on the bed, Levi ran a bath in the claw tub in the master bedroom’s bathroom. The loud rush of water filling the tub was the only sound between them until Eren said, “Do you want me to leave while you, you know?”

With a bored expression, Levi flicked his gaze to Eren. “Be a bit stupid of me to care if you see me shift at this point. You might as well stay. Maybe it’ll scare you off.”

“It won’t,” Eren said firmly. Levi shrugged one shoulder as if to say _suit yourself._

As Levi had requested, Eren went to lay some of their dark towels down on the bed. When he returned the tub was full, and Levi stripped and lowered himself in the water. Eren licked his lips, nerves thrumming. His skin felt electrified with anticipation, goosebumps running up the length of his arms.

Submerged in water, Levi’s body was blurred, but Eren watched as his legs began to fuse together, slowly, at first and then suddenly they were one. That’s when the scales began to form, color blooming into different shades of blue along the tail. Smaller fins emerged at the point where his hip bones would have been and at the end of the tail. His gills were next, opening at the top of his throat as his ears contracted into sharp points, webs appearing between his fingers. Nails becoming clawed and black like a beast’s.   

“Is this really what you want?” Levi asked, the muscles of his abdomen flexing as he hoisted himself into an upright position. Eren caught sight of his sharp incisors as he spoke. There was something even more alluring about Levi like this, the ugliness and power mixed in with all that beauty. The lighter blue fins of his tail fanned themselves at the base of the tub as though testing the air, Levi’s eyes dark and suspicious as he studied Eren.   

A sharp intake of breath as Eren returned the scrutiny. His cock stirred and then strained against his jeans. “Yes.”  

“Well, what are you waiting for? I’m not fucking you like this if you make me army crawl to the bedroom.”

Eren lifted him from the tub, getting used to the new weight in his arms, the slippery feeling of Levi’s wet tail. In his human form, Levi was bulky and muscular already, but his tail was heavier than Eren had expected.

“Careful,” Levi said, voice gentle now. “My fins are sensitive. Make sure they don’t catch on anything.” His arms came up to wrap around Eren’s neck, and Eren could see flecks of gold in the piercing grey of his eyes. Eren swore the color looked different now; the dark grey of his irises lighter.

Eren swallowed and nodded, his mouth dry as he carefully maneuvered them through to the bedroom.

“You remembered the towels,” Levi said appreciatively. He reached for one to dry himself off, leaving another on top of the bed.

“I’m not fucking this up so easily,” Eren replied.

Due to his overeagerness in the past, Eren had accumulated an assortment of embarrassing situations: kneeing Levi in the balls, falling off the bed while changing positions, coming in his pants. This time he would be careful, smooth.

He moved so he was hovering over Levi, hesitant to let his hands wander or to rest his full weight down. But kissing, kissing he could do, so he started there. He slipped his tongue into Levi’s mouth, curious to explore the feel of the newly sharp points of Levi’s teeth, the _otherness_ of it all. His cock throbbed as Levi responded in kind, running his nails down Eren’s back, sucking Eren’s tongue farther into his mouth. Wanting to feel Levi, to see if he was as turned on as Eren, he reached for him only to find...air.  

Eren pulled back and looked between them with a confused frown. “Where’s your dick?”

Levi snorted. “It’s in the slit. I mentioned it before.”

Eren had only a vague recollection of this. They’d never really gone into the mechanics of how this would work. “When does it come out of the slit?” Eren asked, furrowing his brow. He ran a curious finger along the soft edge of the slit, surprised and delighted when Levi gave a full body shiver.

“When you get me excited,” Levi replied.

“Does it excite you when I do this?” Eren murmured, dipping a second finger into the slit. He kissed Levi’s neck, just under his gills, and moved his fingers in slow circles. He could feel Levi’s pulse quickening under his tongue, and when Eren pulled back he could see that Levi had closed his eyes.

He could feel his cock now too, hard and wanting as it emerged from the slit. It was slick with Levi’s arousal and hotter to the touch than Eren had ever felt it before. Though the feeling was different, Eren was pleased to see that it was still recognisable as the same dick he worshiped regularly. He gave it an appreciative stroke, enjoying the warmth spreading through his hand as he glided up and down the slick shaft.

Levi’s tail came up to wrap around Eren’s ass, to pull him closer, and Eren let out a soft moan. The scales were cool and firm against Eren’s skin, a little uncomfortable actually, and it was strange not to be able to tangle his legs with Levi’s.    

“Your tail feels weirdly...strong.”

“There are muscles in there,” Levi said, and squeezed a little tighter. “You not enjoying it? Grass always greener?”

“It’s just taking some getting used to,” Eren admitted. “But no, I think I like it.” He ran his hand from Levi’s human waist down to where his tail began, fingers testing and pressing into the scaled, strong flesh. New and strange and _Levi_.

The corner of Levi’s lips quirked into a small, half-smile, and Eren bent forward to kiss him again. They stroked one another, rubbing their cocks together. He could tell Levi was being more careful with his touch than usual, careful to keep the hooks of his nails from hurting Eren.

“Would it feel good if I went down on you?”

Levi snorted. “What do you think? Don’t be a moron.”

“Be nice or I won’t suck you off,” Eren warned.  

Levi didn’t say a word.

It was strange not to be able to shift down between Levi’s legs. Instead, Eren knelt before Levi on his right side as he began to explore the slit with his tongue, running teasing circles around Levi’s dick.

He ran a hand up Levi’s tail, where his thigh would have been, and inadvertently provoked a full-body shiver from Levi.

With a hiss of pleasure, Levi said, “Do that again.”

“What did I--?”

“Around the fins.”

Eren moved his hand back down and ran his thumb around the soft fins, his tongue still running teasing circles around the base of Levi’s cock.

“Happy you decided to try this tonight?” Eren asked, lifting his head so he could see Levi.

Voice pitched low, Levi said, “I’m coming around.”

Levi’s hips jerked as Eren enveloped him into the tight heat of his mouth, cock ramming down the back of Eren’s throat in his surprised pleasure. It only took a few sucks before Levi tugged Eren’s head up, said, “I need to be inside you.”

Eren turned himself so that he was facing Levi’s tail and eased himself down onto his waiting cock, letting himself be filled to the brim.

Levi groaned softly. “You were ready for me already?”

“Yeah,” Eren said, voice breathless. He’d prepared himself earlier in anticipation for this, biting back his moans in the bathroom as he’d opened himself up, imagining this moment.

As he moved, he bent forward so that he could finger Levi. He timed his movements with Levi's thrusts.

“Jesus fuck,” Levi gasped as Eren added a second finger. “I always thought it was fucked up that my asshole is on the front, but I’m starting to think I was wrong.”

Laughing softly, Eren shifted so he could gain more leverage with his knees and lift himself a little higher. Levi’s hands came to rest on his hips, and he was panting beneath Eren, thrusting up into him with barely contained strength.

“God, you feel so good,” Eren said, pausing his movements. “But I really want to see you now.” He slid off Levi’s cock and turned around to take in Levi, fucked out, forehead damp with perspiration, lips bitten red. His eyes were so dark with lust that Eren let out a soft, breathy moan. “You look so good too.”

He knew he was the only one who had seen Levi quite like this, and he understood what a gift it was. Eren drank him in, he trailed kisses across the part of Levi’s body where the human muscles ended and the blue hues of his tail began. Fingers rubbing that tender area at the base of his fins. It was rare that Levi was vocal in bed, but he kept whispering Eren’s name like it was a surprise each time Eren touched him just right.    

Eren nearly sobbed with pleasure when Levi was inside of him once more and he’d wrapped a hand around Eren’s cock.

“ _Eren_.” Levi gave a bitten-off moan, hips bucking up as he rutted into Eren desperately. The back of his head tipped back, tips of his pointed ears brushing against the headboard.  

Eren could barely formulate words, but he managed to choke out, “Christ you look so fucking beautiful like this. Fuck me harder, _please,_ ” he begged, moving his hips to try to take Levi in deeper.

Maybe this was the only way he’d get Levi to accept a compliment without argument because there was no flippant reply, no changing of the subject. Instead, Levi pulled him forward into a searing kiss. His lips moving against Eren’s like a drowning man, and that was it for Eren. He came in hot, stick bursts all over Levi’s chest, and a moment later Levi gave one final, deep thrust and came too.

 

 

 

“Why now?” Eren asked the next morning. Sunlight flooded the kitchen overlooking the shimmering lake. He was standing by the sink, waiting for his pot of coffee to brew when he’d finally worked up the courage to ask these questions. “Why never before?”

Sometimes Levi could be coaxed into talking about his feelings, but as the silence dragged on, Eren doubted this was one of those times.

Levi took a sip of his tea before finally saying, “I’ve never had sex in my mer form before.”

Eren already knew that piece of information, but he stayed silent and still as he waited for Levi to continue.

“I was afraid if we started you might hate it. It’s part of me, part of who I am. Who the Ackermans are.”

Puzzled, Eren said, “But that’s exactly why I love it. Love you.”

“You also might have loved it too much,” Levi said wryly.

“What do you mean?”

Levi crossed his arms and leaned back in the chair. Light cut across his face, streaking across his cheeks as he sighed. “There’s a world out there of people who are willing to pay good money to fuck someone like me. I don’t want to be someone’s fetish either.”

They’d turned up the heat that morning, but the kitchen hadn’t yet warmed. Eren frowned down at his fuzzy slippers. He couldn’t possibly think of Levi that way, the thought of it completely alien. It pained him to think that Levi had believed that this whole time, that maybe Eren’s own worries had fed into Levi’s fears.

He spoke carefully, “You know it’s been three years, right? And that I’m in this, really in this. It’s not because you’re a shifter or in spite of you being a shifter. That’s irrelevant. I love _you_.”

“Alright,” Levi said, looking into his tea cup as though it was telling him something important.

“If that makes me a fish fucker so be it.”

Levi’s eyes cut to Eren’s and he laughed, his arms dropping by his sides as he relaxed.

Coming to stand before Levi, Eren rested his hands on his shoulders, made him put his tea down. “I meant what I said last night too.”

“What? ‘Fuck me harder, please’?”

“Yeah, and the part where I called you beautiful. You are. All the versions of you.”

“Thanks,” Levi said reluctantly, expression blank. “That’s...good.”

He probably was dying to tell Eren to fuck off, so Eren’s words must have really touched him if that was the reply. Eren grinned. “And I hope we can do it again so I can fuck you next time.”

“Idiot.” Levi tugged Eren onto his lap, laughing quietly as he rested his forehead against Eren’s arm. “We’ll see,” he said.

And that was enough for Eren.

**Author's Note:**

> Thank you so much to SJ, Heidi and Zammy Zam for betaing/feedbacking <3
> 
> Find me on  
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> [Pillowfort](https://www.pillowfort.io/ereri)  
> [Twitter](https://twitter.com/omglevixeren)
> 
> Comments and kudos mean the world <3 I'd love to hear what you think!


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